GNU bug report logs - #23640
25.1.50; Getting rid of compiler warnings

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From: Ken Brown <kbrown <at> cornell.edu>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 23640 <at> debbugs.gnu.org, Paul Eggert <eggert <at> cs.ucla.edu>, Andy Moreton <andrewjmoreton <at> gmail.com>
Subject: bug#23640: 25.1.50; Getting rid of compiler warnings
Date: Mon, 30 May 2016 07:39:47 -0400

On 5/29/2016 6:43 PM, Ken Brown wrote:
> On 5/28/2016 5:47 PM, Ken Brown wrote:
>> On 5/28/2016 2:57 PM, Eli Zaretskii wrote:
>>> emacs_abort is declared with _Noreturn, so how come GCC doesn't shut
>>> up about "unreachable" code?
>>
>> It looks like the problem is the definition of _Noreturn as a macro in
>> config.h.  I'll have to figure out what's going on.
>
> That guess was wrong.  The problem turns out to be that lint is defined
> in config.h.  When lint is defined, Cygwin's <sys/cdefs.h> defines
> _Noreturn to be a macro with empty expansion.  I've raised the question
> on the Cygwin list
> (https://www.cygwin.com/ml/cygwin/2016-05/msg00374.html) as to whether
> that's a bug.

The answer is that the Cygwin's <sys/cdefs.h> is taken from FreeBSD, so 
the problem will exist there too.  (I just checked the FreeBSD git repo 
and confirmed that the code in question is still there.)  So it looks 
like defining lint should be disabled on Cygwin and FreeBSD, at least. 
Or maybe it should only be enabled on platforms where it's known that it 
doesn't cause problems.

Paul, you're the one who introduced this.  What do you think?

Ken

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